$ cabal install primes

Resolving dependencies...
Notice: installing into a sandbox located at /home/christoph/.cabal-sandbox
Downloading primes-0.2.1.0...
Configuring primes-0.2.1.0...
Building primes-0.2.1.0...
Installed primes-0.2.1.0

import Data.Numbers.Primes

Could not find module ‘Data.Numbers.Primes’
Use -v to see a list of the files searched for.

import Data.Primes
import primes
import Primes

echo import Data.Numbers.Primes >foo.hs
cabal exec ghci foo.hs